It strikes me as significant that the very first command God gives the Israelites as they're leaving Egypt is to hold a festival. Most people think of God in the Old Testament as a rule loving overlord ready to zap people for minor infringements, but what do we find here? Oh, sure, there's a "rule," but if the rule is: every year I want you to throw a huge, week long festival; don't work the first day and last day of that festival; take some time to remember that I am a God who loves you enough to battle all the powers that be to free you; oh, and don't forget to have a gigantic meal you get to share with friends and family...sign me up for that rule.
Think about what just happened for the Israelites. When something great happens, something truly good, it's hard to contain it. We get excited about one-handed touchdown passes. The Jews just witnessed Egypt brought to its knees. When the Hebrews left Egypt, the Egyptians practically threw gold, silver, and clothing at them to hurry them along. The Hebrews went from poor to rich, slave to free, literally overnight, so when God says, "tell your children," that 'command' doesn't seem like a very difficult one to follow. Why wouldn't you tell your children?
One last thing about the command to observe the Passover. God doesn't tell the Hebrews to observe the Passover so that they learn he is a God of ridged order and unflinching expectations. God gives the Hebrews the Passover so that why will not forget who he really is: a God of love and protection, a God that will face the enemies too large for them to face, and in so doing bring them life and freedom and celebration. That's what God showed the Jews through the Exodus, and that's what he wants them to learn/remember in the Passover.
The same goes for the consecration of the firstborn. The consecration of the firstborn isn't about sacrifices and following rules; it's about the trust and reliance that people develop when they're continually reminded that they can trust and rely on God. He has shown himself trustworthy and reliable. So why should the Hebrews redeem their firstborn? Simple, because God battled against Egypt's firstborn to set the Hebrews free. God redeemed the Hebrew's firstborn. He will do so again if he needs to. That is a thing worth remembering.
Stopping Point: Exodus 13